“Traction” is a general term that describes the ability of a shoe outsole to resist sliding motion over a surface contacted by that outsole. Traction is particularly important for footwear used in sports and other activities in which a shoe wearer wishes to move quickly and/or to rapidly change movement directions relative to a potentially slippery surface. For an athlete, secure, non-sliding contact between that athlete's footwear and a playing surface can be important for preventing injury and for improving the athlete's performance.
Soccer (also known as “football” outside of the United States), football (also known as “American football” outside of the United States) and other sports are often played on a grass-covered field, a dirt field or some other type of surface that is at least partially penetrable. It is known to include cleats or other traction-enhancing outsole extensions on footwear intended for use in such sports. During running or other actions, these extensions can penetrate the playing surface and help stabilize an athlete's foot from unwanted movement.
Unfortunately, a single cleat configuration for an athletic shoe may not be optimal over a range of conditions in which that shoe will be used. For example, playing surfaces for soccer and many other sports can have extremely variable conditions. If a playing surface is softer and/or more slippery, a larger number of cleats can be useful. When the ground is harder or less slippery, however, fewer cleats may be needed. An athlete may also need more traction during some specific movements (e.g., while running) and less traction during other actions (e.g., while standing).
Although useful to increase traction, outsole extensions can also be sources of discomfort. In particular, a protruding traction element can generate a point pressure on a shoe wearer's foot. An outsole extension that might be useful under some conditions (e.g., when running) may be a source of irritation under other conditions (e.g., when standing). Finding the correct balance between traction enhancement and comfort for cleated footwear thus remains an ongoing challenge.